A 10 year follow-up of 109 patients with histologic Crohn's disease and anal lesions is reported. Fourteen patients (13 percent) have died, 7 from unrelated disorders. Ten required excision of the rectum, but only 5 for perianal disease (4.5 percent). Of the remaining 85 patients, 61 have been followed up to proctoscopy and rectal biopsy. Anal skin tags were still evident in 25 of 37 patients (68 percent), but new tags have appeared in only 2 patients. Ten of 53 fissures (19 percent) were still present at 10 years, and there were no new fissures. Seven of 21 patients (33 percent) still had fistulas but were asymptomatic; the remainder of the fistulas had healed spontaneously (8) or after operation (6). New fistulas have appeared in five patients. None of the patients have been in continent. These results indicate that perianal manifestations of Crohn's disease pursue a relatively benign course and are rarely an indication for proctectomy.